The following built-in functions are always with -mcix or -mcpu=cpu where cpu is ev67 or later. They all generate the machine instruction that is part of the name.

long __builtin_alpha_cttz (long)
long __builtin_alpha_ctlz (long)
long __builtin_alpha_ctpop (long)

The following built-in functions are available on systems that use the OSF/1 PALcode. Normally they invoke the rduniq and wruniq PAL calls, but when invoked with -mtls-kernel, they invoke rdval and wrval.